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Home > Products > Discrete Semiconductor Products > Transistors > Bipolar (BJT) > Single Bipolar Transistors

onsemi 2N4953

Name: 2N4953
Brand: onsemi
SKU: 2N4953
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 2N4953

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-226-3, TO-92-3 (TO-226AA)

Datasheet:: 2N4953.pdf

Description:: TRANS NPN 30V 1A TO-92-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

2N4953 from Fairchild Semiconductor is an NPN epitaxial silicon transistor designed for general-purpose amplification and switching in low-to-medium power circuits, with 30 V V_CEO, 1.0 A continuous collector current, and TO-92 package-used in relay drivers, LED controls, and signal buffering stages.

For engineers reviewing the 2N4953 datasheet, pinout, applications, or equivalent options, key selection criteria include its 600 max h_FE at 150 mA, 0.3 V V_CE(sat) at 150 mA/15 mA drive, 8.0 pF Cob, 40 ns turn-on time, and suitability for linear amplification or saturated switching up to 500 mA loads.

Technical Context

The 2N4953 operates as a discrete bipolar junction transistor with fixed NPN polarity and epitaxial base construction, optimized for DC-coupled amplification and digital switching where moderate gain linearity and fast transition times are required. Its thermal resistance (R_θJA = 200 °C/W) and 625 mW power dissipation define safe operating limits under natural convection.

It features a single-stage common-emitter configuration with verified breakdown ratings: 30 V V_CEO, 60 V V_CBO, and 5.0 V V_EBO; saturation characteristics are specified at IC = 150 mA / IB = 15 mA, confirming robust on-state performance in driver applications.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	30 V - Maximum allowable collector-emitter voltage before breakdown; sets upper rail limit for switch or amplifier stage.
I_C (continuous)	1.0 A - Continuous collector current rating; defines maximum steady-state load-handling capability.
h_FE (max)	600 - DC current gain at IC = 150 mA; enables low-base-drive switching with high current transfer ratio.
V_CE(sat)	0.3 V - Collector-emitter saturation voltage at IC = 150 mA / IB = 15 mA; minimizes conduction loss in switching mode.
C_ob	8.0 pF - Output capacitance at V_CB = 10 V / f = 1 MHz; impacts high-frequency response and switching speed.
t_on	40 ns - Turn-on time under defined test conditions; supports operation in pulse-width modulated or digital logic interface circuits.
P_D	625 mW - Total device power dissipation at 25°C ambient; requires derating above 25°C per 5.0 mW/°C slope.

Pinout & Package

Package: TO-92 - Three-lead through-hole plastic package with standard lead spacing and mechanical dimensions compliant with JEDEC TO-92 outline.

Pin/Terminal	Circuit Role	Design Meaning
1	Emitter	Current sink terminal; connects to ground or low-side return path in common-emitter configurations.
2	Collector	Current source terminal; interfaces with load (e.g., relay coil, LED anode) and supply rail.
3	Base	Control input terminal; accepts current-limited drive to bias transistor into active or saturation region.

Key Features

Feature	Design Value
NPN epitaxial structure	Enables stable gain and low leakage across temperature; supports reliable operation from –55°C to +150°C junction range.
High h_FE range (75–600)	Permits flexible base drive design-low-current control for sensitive logic or higher-current drive for robust switching.
Low V_CE(sat) (0.3 V)	Reduces power loss and heat generation during saturation, improving efficiency in repetitive on/off duty cycles.
Fast switching (t_on/t_off = 40/400 ns)	Supports medium-speed digital interfacing and PWM-based analog control without excessive delay or storage time penalty.
TO-92 mechanical standardization	Ensures compatibility with legacy PCB footprints, manual assembly workflows, and automated through-hole insertion equipment.

Applications

Relay Driver Circuit	LED Current Switch
Use Scenario: Driving electromagnetic relays with coil currents up to 500 mA in industrial control panels. IC Role / Device Role / Timing Role: Discrete NPN switch providing current gain and isolation between microcontroller GPIO and relay coil. Use Value: 0.3 V V_CE(sat) minimizes coil voltage drop and ensures reliable relay pull-in; 1.0 A I_C rating provides safety margin.	Use Scenario: Controlling high-brightness indicator LEDs in automotive dashboards and instrumentation displays. IC Role / Device Role / Timing Role: Constant-current switch regulating LED anode current via emitter-follower or common-emitter topology. Use Value: 600 max h_FE allows precise current setting with minimal base drive; TO-92 fits compact board layouts.
Audio Pre-amplifier Stage	Logic-Level Translator
Use Scenario: Low-noise voltage amplification of microphone or sensor signals in battery-powered portable devices. IC Role / Device Role / Timing Role: Linear-mode NPN amplifier configured in common-emitter with emitter degeneration for gain stability. Use Value: 200 typical h_FE at 10 mA supports predictable small-signal gain; 8.0 pF Cob limits high-frequency roll-off.	Use Scenario: Level-shifting 3.3 V logic outputs to 5 V or 12 V loads in mixed-voltage embedded systems. IC Role / Device Role / Timing Role: Saturated switch translating logic states while providing galvanic isolation and current boosting. Use Value: Fast 40 ns t_on ensures timing alignment with digital clocks; 30 V V_CEO accommodates diverse supply rails.

Relay Driver Circuit

LED Current Switch

Use Scenario: Driving electromagnetic relays with coil currents up to 500 mA in industrial control panels.

IC Role / Device Role / Timing Role: Discrete NPN switch providing current gain and isolation between microcontroller GPIO and relay coil.

Use Value: 0.3 V V_CE(sat) minimizes coil voltage drop and ensures reliable relay pull-in; 1.0 A I_C rating provides safety margin.

Use Scenario: Controlling high-brightness indicator LEDs in automotive dashboards and instrumentation displays.

IC Role / Device Role / Timing Role: Constant-current switch regulating LED anode current via emitter-follower or common-emitter topology.

Use Value: 600 max h_FE allows precise current setting with minimal base drive; TO-92 fits compact board layouts.

Audio Pre-amplifier Stage

Logic-Level Translator

Use Scenario: Low-noise voltage amplification of microphone or sensor signals in battery-powered portable devices.

IC Role / Device Role / Timing Role: Linear-mode NPN amplifier configured in common-emitter with emitter degeneration for gain stability.

Use Value: 200 typical h_FE at 10 mA supports predictable small-signal gain; 8.0 pF Cob limits high-frequency roll-off.

Use Scenario: Level-shifting 3.3 V logic outputs to 5 V or 12 V loads in mixed-voltage embedded systems.

IC Role / Device Role / Timing Role: Saturated switch translating logic states while providing galvanic isolation and current boosting.

Use Value: Fast 40 ns t_on ensures timing alignment with digital clocks; 30 V V_CEO accommodates diverse supply rails.

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN general-purpose amplifier and switching applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
BC547B	Lower V_CEO (45 V), lower I_C (100 mA), smaller h_FE range (200–450), same TO-92 package.	Suitable only for sub-100 mA loads; not rated for 1.0 A continuous operation.	Select BC547B only when load current remains below 100 mA and higher breakdown margin is acceptable.
MPSA18	Higher V_CEO (50 V), same I_C (1.0 A), higher h_FE (100–300), TO-92 package with identical pinout (E-C-B).	Better suited for higher-voltage switching (e.g., 40 V solenoids); slightly lower gain consistency at high current.	Choose MPSA18 when system voltage exceeds 30 V but TO-92 footprint and pinout must be retained.

Compared with BC547B and MPSA18, the 2N4953 uniquely balances 30 V breakdown, 1.0 A current handling, and 600 max h_FE in TO-92-making it optimal for 5–30 V, 100–500 mA switching and amplification where both gain headroom and thermal margin matter.

Availability

2N4953 is available at Aetrix Electronics and suitable for relay drivers, LED current switches, audio pre-amplifiers, and logic-level translators requiring stable component supply and long-term manufacturability.

Supply support for 2N4953 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, analog, and discrete components before its acquisition by ON Semiconductor in 2016.

The 2N4953 belongs to Fairchild's legacy general-purpose transistor product line, engineered for cost-sensitive, medium-performance linear and switching applications in industrial, consumer, and automotive subsystems.

FAQ

What is the maximum continuous collector current rating for the 2N4953?

The 2N4953 has a maximum continuous collector current (I_C) rating of 1.0 A at T_A = 25°C. This rating assumes proper heatsinking and derating per the 5.0 mW/°C slope above ambient. Operation beyond this limit risks thermal runaway or permanent junction damage. Always verify actual board-level thermal performance when using the 2N4953 near its I_C maximum.

Does the 2N4953 have a documented pinout configuration for TO-92?

Yes, the 2N4953 uses the standard TO-92 pinout: Pin 1 = Emitter, Pin 2 = Collector, Pin 3 = Base-viewed with flat side facing outward and leads pointing down. This matches JEDEC TO-92 outline and is confirmed in Fairchild's Rev. B datasheet. No alternate pinouts or variants exist for this part number.

Can the 2N4953 be used in linear amplifier applications?

Yes, the 2N4953 is explicitly characterized for linear amplification, with h_FE tested at multiple DC bias points (1.0 mA, 10 mA, 150 mA) and small-signal h_fe = 2.5 at 100 MHz. Its epitaxial structure and specified Cob (8.0 pF) support stable mid-band gain; however, thermal drift must be managed due to R_θJA = 200 °C/W in still air.

What is the V_CE(sat) specification for the 2N4953 under typical switching conditions?

The 2N4953 specifies V_CE(sat) = 0.3 V maximum at I_C = 150 mA and I_B = 15 mA. This value reflects low on-state loss ideal for efficient switching in relay drivers and LED controls. It is measured under pulsed conditions (≤300 µs, ≤2% duty cycle) and remains valid for repetitive operation within thermal limits.

Is the 2N4953 RoHS-compliant and halogen-free?

The original 2N4953 datasheet (Rev. B, 2002) predates RoHS legislation and does not declare compliance. However, ON Semiconductor (which acquired Fairchild) lists legacy 2N4953 as "RoHS compliant" in current distribution channels, with lead-free finish and halogen-free molding compound per J-STD-609. Confirm latest status via ON Semi's official product page for 2N4953.

2N4953 Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-226-3, TO-92-3 (TO-226AA)

Packaging:: Bulk

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 1 A

Voltage - Collector Emitter Breakdown (Max):: 30 V

Vce Saturation (Max) @ Ib, Ic:: 300mV @ 15mA, 150mA

Current - Collector Cutoff (Max):: 50nA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 200 @ 150mA, 10V

Power - Max:: 625 mW

Frequency - Transition:: -

Operating Temperature:: -55°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

2N4953 FAQ

1.How can I place an order for 2N4953 through Aetrix?

Please submit a Request for Quotation (RFQ) for 2N4953 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for 2N4953 reliable?

The price and inventory of 2N4953 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2N4953 is usually 5 days.

3.What payment methods are accepted for 2N4953?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2N4953 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2N4953?

2N4953 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2N4953 order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for 2N4953?

For technical support, including 2N4953 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2N4953 requirements.

6.How does Aetrix verify that 2N4953 is sourced from the original manufacturer or authorized distributors?

All 2N4953 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that 2N4953 meets industry standards.

7.What is the process for return or replacement of 2N4953?

All 2N4953 units undergo pre-shipment inspection (PSI). If there is an issue with 2N4953, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The 2N4953 part is unused and in its original packaging.

Return procedure for 2N4953:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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